Nozzle for injection of slurry fuels

ABSTRACT

A nozzle for the injection of slurry fuels into a combustion chamber wherein the interior wall of the nozzle is formed of a fine mesh metal screen which is surrounded by a wax or waxlike substance capable of melting at a predetermined temperature.

United States Patent Inventor Harry Levin Woodland Hills. Calif.

App] Nu 733,542

Filed May 31, I968 Patented July 6, 1971 Assignee The Marquardt Corporation Van Nuys, Calif.

NOZZLE FOR INJECTION OF SLURRYFUELS 7 Claims, 4 Drawing Figs.

US. Cl ..239/265.l5, 60/258, 60/2l6 Int. Cl B05!) 1/00 Field of Search 239/128,

132, I32. I 132.3, 265. l5; 60/258 [56] References Cited UNITED STATES PATENTS 2,l75,450 10/1939 lhege 239/128 X 2,560,799 7/1951 Johnson 239/132 X Primary Examiner-M. Henson Wood, Jr. Assisrant Examiner-John J. Love Attorney-Robert E. Geauque ABSTRACT: A nozzle for the injection of slurry fuels into a combustion chamber wherein the interior wall of the nozzle is formed of a fine mesh metal screen which is surrounded by a wax or waxlike substance capable of melting at a predetermined temperature.

NOZZLE FOR INJECTION OF SLURRY FUELS BACKGROUND OF THE INVENTION In any engine which employs fuel injection, some form of a nozzle is employed which injects the fuel into the combustion chamber. These nozzles usually comprise an ascending conical member which results into a small orifice just prior to the combustion chamber. This causes the fuel to be injected into the combustion chamber at a high velocity and in a turbulent condition so even and complete burning of the fuel results. It is common that in many of the engines which employ the fuel injection principle (such as rocket motors and the like), they areto operate for a short period of time and never to be operated again. However, other types of engines require, such as the ram jet engine or certain control engines on rockets, stopping and then restarting one or more times. It is for this type of engine that the device of applicants invention has been primarily designed.

It has always been a major consideration that a fuel com position be selected from which maximum thrust capabilities can be achieved with a minimum amount of fuel weight and volume. It is for these reasons that a slurry type of fuel has been found to be quite advantageous. A slurry fuel is a fuel which is composed of a carrier and particles of a solid substance in suspension. Common types of slurry fuels are high concentrations of either boron or aluminum in suspension with a carrier such as hydrocarbons, alcohols, or polar carrier fluids. Common types of carriers are 225 trimethylhexane, methyl alcohol, or methyl hydrazine. Due to the high density of such fuels, it is common that the small orifice of the nozzle becomes clogged, preventing complete injection of the fuel into the combustion chamber. This situation is especially aggravated when it is required to start and restart the engine one or more times. It is believed that upon the stopping of the engine, the heat from the combustion chamber penetrates back into ,the nozzle structure and orifice which results in the evaporation of the carrier liquid and causing the dry solid particles of the slurry to jam the exit orifice.

Heretofore, there have been attempts to prevent the "drying out" of slurry fuels in fuel injection nozzles. However, such attempts usually include providing an additional carrying liquid or an additional amount of a carrier liquid to the injection nozzle upon stopping of the engine. Usually the apparatus required to provide the additional carrier fluid is substantial and also the timing devices to permit its secretion are extensive. It would be a primary advantage if an injection nozzle could be designed which did not dry out" and accomplished such with a minimum amount of design change and employment of additional apparatus.

SUMMARY OF THE INVENTION The fuel injection nozzle of this invention comprises a nozzle interior portion which terminates in an orifice portion through which the fuel is to be injected into the combustion chamber of an engine. The nozzle interior is funnel-shaped with a smaller diameter of the funnel being nearest the orifice of the nozzle and being substantially the same diameter as the nozzle orifice. The interior wall of the nozzle is composed of a fine mesh metal screen. Surrounding this funnel-shaped screen is a compartment into which can be provided a meltable substance such as a wax material. Also, in certain instances it.may be desirable to employ a polyphenyl ether-type of material.

During the normal injection procedure of the fuel through the nozzle, the material which surrounds the funnel-shaped screening remains solid due to the passing of the fuel through the nozzle which precludes the transfer of sufficient heat from the,- combustion chamber to effect melting of the material. Once the fuel injection is stopped, the temperature of the nozzle rises due to the permitting of heat transfer through the orifice of the nozzle by convection and the heat transfer by conduction through the nozzle structure itself. This meltable material has been selected to become liquid at a temperature slightly below the combustion engine temperature. At this time a small portion of the material liquifies and flows into the nozzle interior and into the nozzle orifice. The inclusion of such a material resists drying out" of the nozzle orifice, thereby preventing the nozzle from clogging due to the solid particles contained in the fuel slurry. Upon engine restart, passage of the fuel through the nozzle orifice is permitted without any hinderance which would be due to a compilation of the solid particles of the fuel slurry.

Although the nozzle of this invention has been described to be employed in conjunction with a rocket or a jet engine, the nozzle of this invention may be also advantageously employed in other similar environments. For example, it is considered feasible that a fuel injection type of engine, which is to operate on a slurry fuel, may be specifically designed for travel upon the surface of the earth rather than through the air. In such an engine, the nozzle of applicant's invention could be advantageously employed.

It is believed from the foregoing that several objects of this invention are apparent other than ones specifically described so as to not warrant specific enumeration. Further, it is be lieved that other objects of this invention will no doubt become apparent from the following specification taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side sectional view of the nozzle of applicant's invention showing the interior nozzle wall and its relation with the nozzle orifice;

FIG. 2 is a plan view of the nozzle as shown in FIG. 1 taken along line 2-2 of FIG. 1;

FIG. 3 is a cutaway sectional view taken along line 3-3 of FIG. I; and

FIG. 4 is a bottom view of the nozzle shown in FIG. 1 taken along line 4-4 of FIG. 1.

DETAILED DESCRIPTION OF THE SHOWN EMBODIMENT Referring particularly to the drawing, there is shown in FIG. 1 a combustion chamber wall 10 having an aperture 12 therein for the retaining of nozzle 14. Nozzle 14 is shown hexagonally shaped which matingly cooperates with aperture 12. The nozzle 14 is to be securely retained by the combustion chamber wall 10 as by welding or any other conventional fastening means, as screw threads or the like. Nozzle 14 is to be supported by the combustion chamber wall 10 so that the top surface 16 of the nozzle 14 is substantially flush with the interior surface 18 of the combustion chamber wall 10. Nozzle 14 includes an inlet compartment 20 and an exit orifice 22. Fuel is to enter the nozzle 14 at the compartment 20, as depicted by the arrows in FIG. 1, and pass through the exit orifice 22 and into a combustion chamber of an engine. After the fuel passes through exit orifice 22, it comes in contact with a spiral nozzle 24 which is secured to the top surface 16 of the nozzle 14. Spiral nozzle 24 functions to diffuse the fuel and spread it over a relatively large area, thereby facilitating even and complete burning of the fuel. Spiral nozzle 24 forms no direct part of this invention and need not be described in more detail. Spiral nozzles are common in the art and any of several types could be employed.

Supportingly held within compartment 20 is a fine mesh screening 26. Screening 26 takes the shape of a truncated cone with a small diameter portion being located adjacent exit orifice 22 and with the large diameter portion being adjacent the inlet opening of compartment 20. The mesh of the screening is to be relatively fine in size as will appear obvious from the following description. However, the mesh size is to be considered a variable, but in any event is to permit passage of a liquid therethrough. In the space between the screening 26 and the walls of the compartment 20, there is to be supplied through opening 28 a meltable substance 30. Substance 30 is to become liquid upon being subjected to the heat energy of the combustion chamber. The meltable substance is first sup plied into compartment 20 in a liquid state and then permitted to harden around screening 26. Once it is hardened the portion of the substance which has penetrated screening 26 is removed prior to usage of the nozzle. 1

It is not uncommon for the combustion chamber temperature for different engines to vary substantially. For example, one type of engine may operate at an average temperature of 700 F. where a second type of engine may operate at 5500 F. Therefore, it is also obvious that the selection of the meltablc substance 30 must also vary with the operating temperature of the engine upon which the nozzle is used. The lower temperature engines are to use a substance which can be classified as a wax or a wax-type of material. Waxes are generally hydrocarbons in nature and can be designed to become liquid anywhere between 100 F. and 1000" F. Where higher temperatures are employed in the combustion chamber (over lOO F.) material 30 would probably have to be of a polyphenyl ether structure. However, it is mainly desired that substance 30 be in the form ofgreasy substance which is capable of being transformed from a solid state into a liquid state at a predetermined temperature.

The operation of the nozzle of this invention is as follows. It will be assumed that the nozzle 14 is installed and ready for operation including a meltable substance 30 about screening 26, fuel is being transmitted through the nozzle'inlet adjacent screening 26 and out through exit 22 and being diffused through spiral nozzle 24 into the combustion chamber of the engine. As long as fuel is being transmitted through the nozzle, meltable substance 30 is maintained in the solid state as the heat energy within the combustion chamber is prevented from raising the temperature of the meltable substance sufficiently to cause it to transform into the liquid state. The fuel acts as a coolingsubstance to remove conductive heat energy from the nozzle structure itself as well as preventing heat transfer by convection through orifice 22.

It is to be remembered that the type of fuel employed here is a slurry fuel; i.e., a fuel which contains a substantial amount of fine solid particles intermixed with a carrier liquid. If it is desired to stop the engine, the fuel being supplied through the nozzle is shut off as by a valve (not shown). The residual heat energy in the combustion chamber quickly transfers to within the exit orifice 22 and into compartment of the nozzle 14. Also, heat transfer by conduction through the structure of the no71le itself is not prevented. Since the meltable substance is chosen to become liquid at approximately the combustion chamber temperature, a portion of substance 30 is melted and passes through screening 26 and is carried forward into exit orifice 22 through the remaining inertial velocity of the fuel. In actual practice only a small portion of substance 30 becomes liquid as the heat energy quickly dissipates to a term perature below which would liquify substance 30. Without the inclusion of substance 30 within the nozzle structure, the residual heat energy would quickly vaporize the carrier liquid of the portion of the fuel contained within the exit orifice 22, causing the fuel to dry out," causing the solid particles of the fuel to fuse together thereby forming a barrier and clogging the nozzle. However, due to the addition of substance 30, this prevents the carrier liquid from drying out and maintains the suspension of the solid particles within the carrier liquid of the fuel.

Minor modifications of this nozzle, varying from the embodiment illustrated and described herein, may be resorted to without departing from the spirit and scope of this invention.

I claim:

I. A nozzle for the injecting of a slurry fuel into a combustion chamber, wherein said slurry fuel is composed of a dense suspension of solid particles in a carrier liquid, said nozzle comprising:

a fuel inlet chamber and an exit orifice to inject said fuel into said combustion chamber; a fine mesh screening being disposed within said fuel inlet chamber, said screening being disposed to come into contact with said slurry fuel and function as a walled passage therefor; and

a meltable substance being disposed between said screening and the wall of said inlet chamber, said meltable substance being capable of becoming liquid upon being subjected to the operating temperature of said combustion chamber, whereby upon stopping the flow of said slurry fuel through said nozzle some of the combustion chamber heat energy is transferred within said exit orifice and said fuel inlet chamber and causes a portion of said meltablc substance to become liquid and pass through said screening.

2. An apparatus as defined in claim 1 wherein:

said fuel inlet chamber having an aperture to facilitate the entry of said meltable substance.

3. An apparatus as defined in claim 2 wherein:

said screening being in the shape of a truncated cone, the smaller diameter section of said truncated cone being located directly adjacent said exit orifice.

4. An apparatus as defined in claim 3 wherein:

said meltable substance comprising a hydrocarbon wax.

5. An apparatus as defined in claim 3 wherein:

said meltable substance comprising a composition of a polyphenyl ether.

6. An apparatus as defined in claim 3 wherein:

said slurry fuel including a carrier liquid and boron particles.

7. An apparatus as defined in claim 3 wherein:

said slurry fuel including a carrier liquid and aluminum particles. 

1. A nozzle for the injecting of a slurry fuel into a combustion chamber, wherein said slurry fuel is composed of a dense suspension of solid particles in a carrier liquid, said nozzle comprising: a fuel inlet chamber and an exit orifice to inject said fuel into said combustion chamber; a fine mesh screening being disposed within said fuel inlet chamber, said screening being disposed to come into contact with said slurry fuel and function as a walled passage therefor; and a meltable substance being disposed between said screening and the wall of said inlet chamber, said meltable substance being capable of becoming liquid upon being subjected to the operating temperature of said combustion chamber, whereby upon stopping the flow of said slurry fuel through said nozzle some of the combustion chamber heat energy is transferred within said exit orifice and said fuel inlet chamber and causes a portion of said meltable substance to become liquid and pass through said screening.
 2. An apparatus as defined in claim 1 wherein: said fuel inlet chamber having an aperture to facilitate the entry of said meltable substance.
 3. An apparatus as defined in claim 2 wherein: said screening being in the shape of a truncated cone, the smaller diameter section of said truncated cone being located directly adjacent said exit orifice.
 4. An apparatus as defined in claim 3 wherein: said meltable substance comprising a hydrocarbon wax.
 5. An apparatus as defined in claim 3 wherein: said meltable substance comprising a composition of a polyphenyl ether.
 6. An apparatus as defined in claim 3 wherein: said slurry fuel including a carrier liquid and boron particles.
 7. An apparatus as defined in claim 3 wherein: said slurry fuel including a carrier liquid and aluminum particles. 